Your motherboard is running SATA 6Gb/s, which is SATA III. If you are not aware, the SATA interface is backwards compatible. You can put a SATA I device on a SATA III port and vice versa. However, each iteration of SATA introduces more bandwidth for your devices. So, pairing a SATA III SSD with a SATA III port would yield the best performance for you.
As far as SSDs go, I happen to think that the best bang for your buck is currently the Samsung 840 Evo family. However, the 850 Pro line came out not too long ago and there are whispers of an 850 Evo family.